When a designer wants to build a Natural Language Understanding (NLU) model for a new application (e.g., an airline reservation system), the designer starts a new project and configures that project with an ontology. The ontology is an an organizing structure of concepts that the NLU application handles. For example, a project may handle fields such as DATE, LOCATION, DATERANGE, or AMOUNT, etc. Typically, NLU models for many of these concepts are built-in within a designer portal and other more specialized NLU models (such as the airplane seating types for a particular airline) may need to be created by the designer.